The present invention relates to the preparation of triethylenediamine (TEDA) and piperazine (PIP) by contacting nitrogen-containing compounds with zeolites at elevated temperature.
The synthesis of TEDA and PIP from a variety of amine compounds using metallosilicates is well known in the art.
U.S. Pat. No. 3,956,329 discloses a process for preparing TEDA from a number of amine compounds using untreated zeolite catalysts with a SiO.sub.2 /Al.sub.2 O.sub.3 (silica to alumina) ratio between 2 and 12.
U.S. Pat. No. 4,804,758 discloses the preparation of TEDA from certain heterocyclic amines in the presence of borosilicate and/or iron silicate zeolites as catalysts.
U.S. Pat. No. 4,966,969 and 5,041,548 disclose the preparation of TEDA from amine compounds using a catalyst comprising a crystalline metallosilicate having a silica/metal oxide molar ratio of 12/1 or more, in particular, a metallosilicate crystallized in the presence of an organic crystallizing agent.
EP 158 319 discloses a method of preparing TEDA by contacting acyclic or heterocyclic amines with untreated high-silica zeolite having a silica to alumina ratio of at least 20 to 1.
EP 382 055 discloses a process for synthesizing TEDA from ethylenediamine and 0 to 200 mole % PIP on aluminum, boron, gallium and/or iron silicate zeolites.
EP 423 526 discloses the preparation of TEDA and PIP from ethylenediamine-water mixtures which is catalyzed by zeolites of the pentasil type with weakened acidity, i.e., which contain alkali metal ions or in which the aluminum of the zeolite skeleton has been isomorphously replaced by iron.
EP 312 734 discloses that PIP can be converted directly to TEDA in the presence of untreated zeolites having a pentasil, especially a ZSM-5, structure.
EP 313 753 discloses the preparation of mixtures of TEDA and PIP from polyethylene polyamines and/or ethanolamines using an untreated pentasil zeolite.
Journal of Catalysis (vol. 144, p556-568, 1993) describes the use of pentasil type zeolites for TEDA synthesis from a variety of polyamines.
Selectivation of zeolites with silicon compounds has been used for improving catalytic properties of some specific processes:
U.S. Pat. No. 5,365,004 discloses zeolite catalysts which have been modified by being ex situ selectivated with a silicon compound to improve their catalytic properties for hydrocarbon conversions such as toluene disproportionation process.
EP 593, 086 discloses treatment of mordenite zeolite with tetraethyl orthosilicate (TEOS) to improve the selectivity for methylamine synthesis.